code: def test_gap_no_interpolation():
      data = _random_grid(3, 2)
      data.loc[4, "y"] = 3
      p = ggplot(data, aes("x", "y", fill="g")) + geom_raster()
      # Warns about uneven vertical intervals
      with pytest.warns(PlotnineWarning):
          assert p == "gap_no_interpolation"
  
file_path: plotnine/tests/test_geom_raster.py
imports: import numpy
  import pandas
  import pytest
  from plotnine import aes, geom_raster, ggplot
  from plotnine.exceptions import PlotnineWarning
label_desc: Use image node_id 4 for calling a global function with example usage: test_gap_no_interpolation() without return types